The plasmonic properties of bimetallic (gold and silver) core-shell nanostructures were studied numerically by using the boundary element method implemented in MATLAB (MNPBEM toolbox). The dependence of the bulk refractive index sensitivity of the nanostructures on the core/shell thicknesses was investigated, and regions of enhanced sensitivities were identified for both Ag@Au and Au@Ag type of nanostructures. For Ag@Au nanoparticles, utilizing a 14 ± 2 nm silver core radius with 4 ± 2 nm gold shell thickness or a 22 ± 2 nm core radius with 6 ± 1 nm shell thickness can yield a 1.2–2.5× increase in sensitivity compared to a purely silver nanosphere with the same size. For Au@Ag structures, 20 ± 3 nm gold core size with 10 ± 3 nm silver shell thickness was found to be optimal, with sensitivity enhancements between 2 and 5× compared to pure gold nanoparticles with the same size. The increased sensitivity can always be attributed to the hybridization of the plasmon absorbance peaks corresponding to the silver and gold parts, which merging comes with increased peak width (and thus decreased figure of merit) as a tradeoff. The provided sensitivity maps can be helpful for the design and fabrication of plasmonic sensors utilizing core-shell nanostructures.

通过使用在MATLAB（MNPBEM工具箱）中实现的边界元素方法，对双金属（金和银）核-壳纳米结构的等离子体性能进行了数值研究。研究了纳米结构的体折射率灵敏度对核/壳厚度的依赖性，并且确定了Ag @ Au和Au @ Ag型纳米结构的灵敏度提高的区域。对于Ag @ Au纳米粒子，利用14±2 nm的银核半径和4±2 nm的金壳厚度或22±2 nm的核半径和6±1 nm的壳核，可以使灵敏度提高1.2–2.5倍。具有相同大小的纯银纳米球。对于Au @ Ag结构，发现金壳尺寸为20±3 nm，银壳厚度为10±3 nm是最佳的，与相同大小的纯金纳米粒子相比，灵敏度提高了2到5倍。灵敏度的提高始终可以归因于对应于银和金部分的等离激元吸收峰的杂化，这种合并伴随着峰宽的增加（因此品质因数降低）作为一种折衷。所提供的灵敏度图可有助于利用核-壳纳米结构的等离子传感器的设计和制造。